Field of the Disclosure
The disclosure generally relates to a substrate structure and a manufacturing process thereof, and more particularly, to a substrate structure having a component-disposing area and a manufacturing process thereof.
Description of Related Art
In recent years, with ever-changing advances in electronic technology, high-tech electronics industry appeared one after another, which makes the more humanized and better in function electronic products continue to be launched. And these electronic products are developing toward the light, thin, short and small figure design. Usually in these electronic products, a circuit substrate is disposed for carrying single electronic component or a plurality of electronic components. However, disposing the electronic components on a circuit substrate will result in an increase of carrying area, and thus how to make the electronic components hidden in the circuit substrate has become a key technology in today.
In the prior art, to bury the components in a substrate, it needs to form an open hole in a core layer by laser drilling or mechanical drilling, followed by disposing the components in the open hole. However, the components must be electrically connected to the circuit layer of the circuit substrate through pads, and thus, a solder mask layer must be formed in advance in the process at the position where the open hole is disposed to facilitate the successive process of pads. In particular, the process should be performed separately from other processes of the circuit substrate, which makes the process more complicated. Specifically, during the laser drilling for the open hole, the penetrating depth of laser must be controlled very accurately to avoid penetrating the solder mask layer by drilling or having residue of the solder mask layer. All the above-mentioned issues increase the fabrication difficulty of the circuit substrate having components disposed therein. In addition, since the thickness of a core layer is usually less than 100 microns (μm), which is also a great challenge for today's solder-resist fabrication.